Will I be taxed short term capital gain if I sell partial for less than cost basis?

For example: if I buy a stock for $10,000 and it increases to $30,000 and I then proceeded to sell $9,999 worth of my position (1 dollar less than cost basis) will it trigger a short term tax event? Will the remaining $20,001 still qualify for long term capital gain when the threshold is passed? Thanks.